“As more outside groups get involved in the war, each escalates by backing their side, then a rival will also get involved to back the other side. So what you have is not just the Syrian factions escalating, but regional and global powers escalating as well, thus worsening the war and entrenching Syria’s divisions.

You’ll also see that the countries getting involved don’t always have the same objectives, and can end up working against even their allies. When Gulf states begin funding Syria’s rebels, for example, they are mostly seeking to topple Assad and set back his patron, Iran, so they often fund extremists, believing they’re better fighters. And different Gulf states fund different groups — at first Qatar is the most active, then Saudi Arabia — that are sometimes at odds with one another. And so on. These internal contradictions are an important part of understand how the war has gotten so bad.”

“For more, read the brief history of Syria’s war, from the rise of the opposition to the refugee crisis to why the US and Russia ended up intervening.”